This invention relates to nucleic acid and amino acid sequences of a novel H-rev 107-like protein and to the use of these sequences in the diagnosis, prevention, and treatment of cancer and autoimmune disorders.
Neoplastic transformation of cultured cells is a commonly used model for the study of cancer development. Cells may be transformed by a genetic change in a proto-oncogene or through the introduction of an oncogene into the cell. The transformed cells have a complex syndrome of proliferation related abnormalities, such as: lack of density-dependent inhibition of cell division; lack of anchorage dependence; altered shape and adherence; lack of growth factor dependence; lack of eventual senescence; and the ability to give rise to tumors when injected into suitable host animals.
Cells that retain expression of the oncogene yet revert, either fully or partially, to the non-transformed phenotype, are known as revertants. Reversion can be triggered by inactivation of an effector molecule necessary for relaying oncogene mediated signals or by inactivation of an oncogene processing protein. Alternatively, reversion can be triggered by the introduction of a dominant tumor suppressor gene. For example, it is known that the wild type p53 gene or the retinoblastoma gene suppresses the proliferation of various transformed cell lines.
Schafer R. et al. described the partial reversion of the transformed phenotype in H-ras transfected tumorigenic cells by transfer of a human gene (1988, Proc. Natl. Acad. Sci. 85: 1590-1594). The H-ras transformed 208F rat fibroblasts (FE-8 cells) were cotransfected with genomic DNA from human placenta and a plasmid conferring hygromycin B resistance. Treatment with hygromycin and ouabain eliminated non-transfectants and cells with a transformed phenotype. The remaining clones had lost the morphology of transformed cells and required anchorage for growth. The isolated clones had reduced tumorigenicity in nude mice, yet they continued to express the p21 RAS protein, although at a reduced level (Schafer, supra). One such revertant clone, named F9, would not grow in semi-solid growth medium, yet it contained multiple copies of the H-ras gene.
A novel gene, rat H-rev107, was isolated from F9 cells by subtraction cloning (Hajnal, A. et al., (1994) Oncogene 9: 479-490). H-rev107 encodes a protein of 18 kDalton without structural homology to known proteins, other than a simultaneously reported human homolog (Hajnal et al., supra). H-rev107 protein is thought to be localized to the inner cell membrane, although it has also been found in the cytoplasm. Diminished expression of H-rev107 may be closely associated with loss of density-dependent growth inhibition and, more generally, with neoplastic growth.
Since, introduction of H-rev107 into transformed cells did not consistently induce reversion, H-rev 107 is probably not a dominant tumor suppressor gene. Nonetheless, H-rev107 expression contributes to stable reversion and has been used to distinguish normal from neoplastic tissues (Hajnal et al., supra).
Discovery of proteins related to H-rev107 and the polynucleotides encoding them satisfies a need in the art by providing new compositions useful in diagnosis, prevention, and treatment of cancer and autoimmune disorders.
The present invention features a novel H-rev107-like protein hereinafter designated HREVP and characterized as having similarity to H-rev107.
Accordingly, the invention features a substantially purified HREVP having the amino acid sequence shown in SEQ ID NO: 1.
One aspect of the invention features isolated and substantially purified polynucleotides that encode HREVP. In a particular aspect, the polynucleotide is the nucleotide sequence of SEQ ID NO:2.
The invention also relates to a polynucleotide sequence comprising the complement of SEQ ID NO:2 or variants thereof. In addition, the invention features polynucleotide sequences which hybridize under stringent conditions to SEQ ID NO:2.
The invention additionally features nucleic acid sequences encoding polypeptides, oligonucleotides, peptide nucleic acids (PNA), fragments, portions or antisense molecules thereof, and expression vectors and host cells comprising polynucleotides that encode HREVP. The present invention also features antibodies which bind specifically to HREVP, and pharmaceutical compositions comprising substantially purified HREVP. The invention also features the use of agonists and antagonists of HREVP. The invention also features a method for producing HREVP using the host cell, and methods for treating cancer and autoimmune disorders by administering an agonist to HREVP.